This application claims the priority of German Application No. 198 32 868.0, filed Jul. 22, 1998, the disclosure of which is expressly incorporated by reference herein.
The invention relates to a latching element like that which can be used, for example, for locking a selector lever in vehicles, a method for manufacturing such a latching element, and the use of the latching element.
Latching elements can have comparatively large structural volumes when the latching forces received and transmitted reach a certain magnitude. Thus, for example in a latching element used in conjunction with a selector lever in a vehicle, latching forces on the order of 1500 N are developed with a force of 300 N to be latched at the lever.
To transmit such high latching forces, the material cross section of a latching element must be increased. This has the disadvantage that such a latching element is difficult to manufacture; for example, manufacturing a latching element of this kind by punching is economically possible only up to a certain thickness of the sheet metal. In addition, finishing work is required because thick parts cannot be punched with the same precision as thin parts. A multilayer latching element of this kind is already known from a key lock device used in vehicles of the Porsche 964 Tiptronic model.
If the latching element is made of metal, there is also the problem that when the latching element strikes other latching parts, such as a latching pawl, an impact or other similar noises are generated.
It is thus the goal of the present invention to provide a latching element that is suitable for accepting high forces, can be manufactured at low assembly cost, and exhibits reduced noise development in conjunction with additional latching parts.
This goal is achieved according to the present invention by providing a latching element consisting of at least two flat elements, characterized in that the first element is injection-coated at least areawise with elastic material and the other elements are coupled with the first element by the elastic material. A method for making latching elements includes the steps of injection coating a blank for a first flat element with elastic material; applying other elements; and fastening the other elements by compressing the elastic material. An especially advantageous application of the present invention is proposed in which the novel latching element is used in a selector lever.
According to the invention, it is proposed for a device technology solution to this prior art problem to make the latching element consist of at least two flat elements. The first element is injection-coated at least areawise with elastic material, and other elements are coupled with the first element by the elastic material. The fact that the latching element is assembled from a plurality of flat elements reduces assembly cost, since the individual flat elements are thinner and therefore much simpler to manufacture. In addition, a latching element of this kind can be adapted especially simply to the latching forces that develop, with the number of flat elements of which the latching element is composed being variable. By injection-coating a first flat element with elastic material, the individual flat elements do not abut one another directly, but are decoupled by the elastic material. The other flat elements are connected with the first flat element by means of the elastic material, so that no additional connecting means are required. The elastic material produces a significant noise reduction both by damping the impact upon contact with additional latching parts and also by decoupling the individual flat elements. Moreover, the elastic coupling of flat elements has the advantage that the individual flat elements can align themselves with respect to one another so that the latching force is distributed over all of the flat elements and, hence, is received without force peaks. The flat elements are self-aligning. The first element does not have to be injection-coated over the entire surface but it is sufficient instead if this is performed areawise to the extent necessary on the contact surfaces and also in specified areas that are intended for coupling with the other flat elements.
Advantageous improvements on the latching element are described herein.
Thus, the elastic material used as the coupling element passes through the other elements. With this type of coupling of the flat elements with one another, only the first flat element need be injection-coated, while the other elements are coupled with the first flat element by the elastic material. This coupling can be performed for example by shapewise connection (undercutting, latching, etc.) or by compressing the elastic material.
It is also contemplated to provide means for limiting elastic deformation. Since elastic material can be applied to the first flat element only with a material-dependent minimum layer thickness, as a result of the thickness of the elastic material, an inadmissibly high deformation travel results between the individual flat elements under high loads. It is proposed to provide means for limiting the elastic deformation that can be applied to one or to all of the flat elements.
Together with the other latching parts, the contact surfaces of the latching element serve to latch the latching element. Regarding the contact surfaces, a portion of the contact surfaces is not injection-coated. This applies in particular to contact surfaces that cooperate with other latching parts as latching pawls. In this case, it is not desirable to accept even higher latching forces under the circumstances that an elastic material is applied between the surfaces that transfer the latching force. Moreover, the noise that results when a metallic latching pawl contacts the metal latching surface can be used to indicate acoustically the engagement of the latching pawl.
Another design of the contact surfaces provides that the first flat element, injection-coated with elastic material, has a recess in the area of the contact surface that is set back relative to the other flat element in the vicinity of this contact surface. The first flat element is injection-coated with elastic material in the vicinity of the contact surface in such fashion that the elastic material projects beyond the surface that contacts the other elements. In this design, an elastic stop is formed on the injected flat element, said stop projecting beyond the contact surface formed on the other flat elements. An engaging latching part thus first contacts this elastic stop and any impact of the latching part is damped. If the forces acting under these circumstances are high enough, the elastic stop will be deformed to the point where the latching part abuts the contact surfaces formed on the other flat elements. Further deformation of the elastic stop is now no longer possible; on the other hand, the elastic stop cannot be destroyed since the recess provided in the injected flat element offers sufficient space to receive the deformed elastic stop without the latter being inadmissibly deformed.
The method for manufacturing latching elements according to the invention, in a first step, comprises the injection of the first flat element with elastic material. In a second step, the other flat elements are then placed on the first flat element. If necessary, in the final step all of the flat elements can be connected into a packet by compressing the elastic material that passes through the other elements.
Regarding the injection of the first flat element, in an improvement on the manufacturing method, it is proposed to produce the recess inside the injection coating by leaving it open during the injection coating process. Alternatively, it is proposed to produce a recess of this kind only after injection coating, for example by removing the injected material.
Since only the first element is injection-coated with elastic material, the stop surfaces injection-coated with elastic material are effective only in the event that the elastic material is applied. It is only when the force acting on the stop surface is so high that the elastic material is pushed away that the other elements besides the first element continue to support and accept the latching force.
The use of the latching element according to the invention is especially advantageous in a selector lever like that provided conventionally in a motor vehicle for operating an (automatic) transmission. Since a selector lever of this kind is located in the interior of a vehicle, noises emanating from such a selector lever can be heard especially clearly and therefore are especially annoying. It is also advantageous if the latching element is used to lock the selector lever, since latching elements in selector levers normally have the task of providing protection against misuse of the vehicle, possibly against theft. The forces developed at the selector lever under these conditions can be very high and are further reinforced by the prevailing geometric conditions (lever arm of selector lever). This applies in particular when the latching element is connected directly with the selector lever.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings.